Ceramic rod spacers for use in mass producible electron tubes



March 21, 1961 5, 555 ETAL 2,976,452

ELECTRON TUBES CERAMIC ROD SPACERS FOR USE IN MASS PRODUCIBLE Filed NOV. 4, 1954 5 Sheets-Sheet 1 Ma 1961 M. E. WEISS ETAL 2,976,452

CERAMIC ROD SPACERS FOR USE IN MASS PRODUCIBLE ELECTRON TUBES 5 Sheets-Sheet 2 Filed Nov. 4, 1954 INVENTORS CRAIG M. GARRETSON g- EMORTIMER E.WE\SS ATTORNE;

March 21, 1961 M. E. WEISS ETAL 2,976,452

ELECTRON TUBES CERAMIC ROD SPACERS FOR USE IN MASS PRODUCIBLE Filed Nov. 4, 1954 5 Sheets-Sheet 3 cams GARRETSON MORTIMER E.WE|SS B1 JTT EY March 21, 1961 M. E. WEISS EI'AL 2,976,452

cam/11c ROD SPACER-'5 FOR "USE IN MASS PRODUCIBLE ELECTRON TUBES 5 Sheets-Sheet 4 Filed Nov. 4, 1954 NVENTORS FtgJ5 came M. GARRETSON MORTIMER E. wuss BY My ATTOR March 21, 1961 M. E. WEISS EI'AL CERAMIC ROD SPACERS FOR USE IN MASS PRODUCIBLE ELECTRON TUBES 5 Sheets-Sheet 5 Filed Nov. 4, 1954 United States Patent Oflice Patented Mar. 21, 1961 CERAMIC ROD SPACERS FOR USE IN MASS PRODUCIBLE ELECTRON TUBES Mortimer E. Weiss, Flushing, and Craig M. Garretson, East Norwich, N.Y., assignors, by mesne assignments, to Sylvania Electric Products Inc., Wilnungton, Del., a corporation of Delaware Filed Nov. 4, 1954, Ser. No. 466,888 Claims. (Cl. 313-257) This invention relates to the use of ceramic rods, which may be metal cored, in electron tubes to obtain the requisite spacing between elements of the tubes.

In conventional tube manufacture spaced perforated ceramic or thin mica spacers are employed, these being threaded over elements of the tube to align and space them properly. These spacers, particularly if they be of the mica type, are fairly dificult to apply to the tube elements to be spaced apart and in so applying them to the tube elements edges of the holes may break away with consequent poor performance of the finished tube or with loss of time and material in replacing the spacers before further manufacturing operations on the tube takes place. Furthermore, use of these perforated spacers does not lend itself to high uniformity of tube characteristics, nor, due to the character of the material, to such ruggedness as can be attained by the use of the ceramic rod spacers of this invention, as will be described. Moreover, the use of insulating rods as spacers enables compact assembly of closely spaced parts leading to the manufacture of tube mounts of small dimensions and low inertia and to obtain electrical characteristics not possible with conventional structures. The use of metallic rods with insulating coating thereon has the added advantage of affording electrical and heat conducting means for some of the electrodes and of insulated support for others of the electrodes.

It is an object of the invention to provide for ease and cheapness in manufacture of tube mounts.

It is a further object of the invention to provide means whereby uniformity of tube mount manufacture may be attained.

It is a still further object of the invention to provide an electrode package wherein basic spacer elements are insulating rods.

It is yet another object of the invention to make the rods with electroconductive cores so that they function not only as means about which the electrodes may be compacted but also as conductive elements as between electron tube parts and the stem leads of the tube base.

These and other objects of the invention will be apparent after reading the following specification and claims when taken in conjunction with the accompanying drawings in which:

Fig. 1 is a side view of a tube mount with portions broken away to expose hidden parts.

Fig. 2 is a top view of the mount.

Fig. 3 is a side view of the tube mount taken at right angles to Fig. 1.

Fig. 4 is a section through the mount on the line 4--4 of Fig. 3.

Fig. 5 is a view similar to Fig. 1 showing a tube mount with a modified form of assembly.

Fig. 6 is a section through Fig. 5 on the line 66 thereof.

Fig. 7 is a side view of the tube mount of Fig. 5 at right angles thereto.

Fig. 8 is a top view of the tube mount at Fig. 7.

Fig. 9 is a side view of another modification of a tube mount manufactured in accordance with this invention, parts being broken away to expose hidden portions.

Fig. 10 is a section of the mount of Fig. 9 on the line 10-19 thereof.

Fig. 11 is a view of the mount at right angles to Fig. 9, with parts broken away.

Fig. 12 is a top plan view of Fig. 11.

Fig. 13 is a side view of still another modification of a tube mount made in accordance with the invention, showing how an electron tube utilizing more than three electrodes may be spaced apart by insulating rods. A filament tensioning spring is removed for simplicity of illustration.

Fig. 14 is a section of the mount of Fig. 13 on the line 1414 thereof.

Fig. 15 is a view of the mount taken at right angles to the Fig. 13 position.

Fig. 16 is a section of the line 16-16 of Fig. 15.

Fig. 17 is a side view of yet another modification of a tube mount made in accordance with the invention, showing how an electron tube utilizing more than three electrodes may be made in a fashion other than that set forth in the previous species.

Fig. 18 is a view of the mount at right angles to the position shown in Fig. l7.

Fig. 19 is a section on the line 19-19 of Fig. 18, and

Fig. 20 is a section on the line 20-20 of Fig. 18.

Considering the figures in greater detail in Figs. 1 to 4 is disclosed one form of the invention.

In this form there is disclosed a stem 30 to which is welded a stack assembly 32. The stack assembly comprises pairs of spacer rods 34, a grid 36, a pair of anode plates 38, a pair of straps 40, a filamentary type cathode 42 and a getter 44.

The spacer rod of a pair is made up of a metallic rod held to close tolerance as to diameter bent into shape with the arms of the U covered with insulating material 46, preferably ceramic material such as alumina. The insulating material is also held in close tolerance as to thickness so as to facilitate reproducible spacing and therefore electrical characteristics of the tube. The free ends of the U and the bight or bend of the U is left bare. The grid 36 is a two part frame with wire 50 wound about the parts. Each frame half is generally rectangular in plan, two of the sides 52 of each frame being in contact with the corresponding sides of the other frame and the ends 54 being offset away from each other to provide passage through the grid of the filamentary cathode 42.. The grid Wires are wound taut about the two frames and the grid laterals on one frame are spaced apart from the grid laterals on the other grid frame by the thickness of the two frames. The filament 42 passes through the interior of the grid laterals without touching the same. One of the sides of each grid frame is prolonged as at 56 for attachment to a stem lead.

The grid is positioned between the two U-shaped ceramic covered rods with the ceramic material on the rods interposed between the grid and metal of the rods.

On each side of the U-shaped ceramic covered rods is an anode plate 38. Each plate is generally rectangular in form with channels 58 formed on the long edges of the rectangles. These channels partially embrace the ceramic coating on the rods and serve to position the plates laterally relative to the rods and also position the plates at a fixed distance from the grid.

Girding the assemblage of grid, U-shaped rods and anode plates are the two narrow metallic straps 40. The straps are each U-shaped members with arms of unequal length and with outturned flanges 60. The flanges of one strap are welded to the flanges of the other strap,

the straps being of such rigidity as to firmly clamp the grid, side rods and plates together. This provides for a rigidly held together compact electrode assembly.

Welded on two of the rods 34 is the tension spring support 62, this being a generally H-shaped member, laid on its side, with one leg of the H broad enough to serve as an attaching means to the side rods and as a tacking surface to which may be welded a filament tensioning spring 64. This spring is coiled about the narrow leg of the H-shaped member and pulls upwardly on the bight of the cathode filament 42. The lower ends of the filament have tabs 66 welded thereto.

The electrode assembly is mounted on the leads of the stem in any position desired. It is here shown as having the connecting bend of the rods welded to two of the stem leads 68 and 70. The grid frame is welded to another lead 72 of the stem by means of the grid frame prolongation 56. The straps 40, which are in electrical contact with the anode plates, are welded to two long stem leads 74 one on each side of the strap flanges 60. The filament tabs 66 are pulled down to exert tension on the spring 64 and are welded to an angled portion of stem lead 68. It will he noted that current is supplied from the stem lead 68 to the parallelly connected filament sections through a spacer rod, the current flowing from stem lead 68 to the two tabs, the filament 42, the spring 64, spring support 62, a spacer rod 34 and stem lead 70. The unfiashed getter is supported between the long stem leads 74 near the upper ends thereof and initially is in circuit with the spacer rods.

It will be noted that with the above described construction, no mica or other fragile spacers are employed and that electrode elements are held rigidly together in properly spaced relation by the insulated rods and straps. Since the rods and the insulation thereon can be held to close tolerances, the electron device can be built with reproducible electrical characteristics with much more exactitude than where perforated spacers are utilized and in which the perforations may in assembly or in tube use become enlarged to vary the spacing between elements. Moreover the package arrangement disclosed lends itself to ease in automatic assembly.

In the species of invention disclosed in Figs. 5 to 8 substantiallly the same form of stem, grid, tension spring support, tension spring and filament are employed. However, in this modification the plate anodes themselves bind parts together. The grid frames, as before, have prolongations 156 secured to a stem lead 172. The anode plates 138, 138, as before, have channels 158 but these are now not at the edges of the plates, but inwardly thereof. The plates beyond the channels are bent toward each other and are provided with flanges 159 parallel to and welded to one another to firmly clamp the grid frames to the ceramically coated rods. The stacked electrode assembly in this modification also includes two metallic angles 176, each having one leg welded to a plate 138 and another leg provided with a channel 178 running along the edge of the leg.

The stacked electrode assembly is mounted on the stem assembly by welding the channels 178 to stem leads 174 and making suitable electrical connection of the electrode elements to the other stem leads. As before, getter 144 is welded to stem leads 174. This species of invention simplifies the formation of the stacked assembly since the plates themselves perform the function of both plates and straps in the first described embodiment. Also the plates extend over a longer length of rod than the straps do in the first species and therefore provide for a more rugged structure.

In the species disclosed in Figs. 9 to l2 only a single pair of straight insulated rods 234 is employed. These rods are preferably metallic rods insulated as heretofore described, the ends being bare of insulation. The filamentary cathode 242 is of the same construction as heretofore. The grid 236 is substantially the same as in the previous form, the difference residing in the provision of wings 237, one at each corner of each grid frame. These wings, when the two frames of the grid are in abutting relation, are divergent from one another and accommodate between them the insulated rods. The grid frames, as before, have prolongations 256 welded to each other and to a stem lead 257 extending up from wafer 230. The anode in this species comprises two plates 238 and 239. The plate 238 is generally U-shaped with outwardly turned flanges 241. The U-shaped plate at its bend snugly engages an insulated rod 234 and then the arms of the plate are offset to provide clearance between them for the grid. The flanges 240 are channeled at the edges, as at 258, and are Welded to stem leads 268 extending upwardly from wafer 230. The plate 239 has a central channel section 240 embracing a rod 234 and welded at arcuate lateral edges to the stem leads 268.

The cathode tension spring support 262 is welded to the upper bare end of one of the rods 234, the lower end of the rod being welded to a stem lead. The lower ends of the cathode filament are welded via the tabs to still another stem lead. The unfiashed getter 244 is welded to the two stem leads 268. All of the above provisions makes the construction of this packet very rugged and with but few parts.

In the species disclosed in Figs. 13 to 16 there is disclosed still another embodiment of the invention. Here there is disclosed a tetrode involving a cathode, two grids, and an anode.

As in the previous species, only two insulated rods 334 are employed. The control grid structure 336 with its wings 337 and its projections 356 and the cathode structure 342 are as described in conjunction with the previous species. Anode plate 338 in this species, has its parallel portions spread apart a greater distance than in the previous species to accommodate a second grid 386. The connecting or base portion of the U-shaped anode is channeled to partially encompass the insulated rod 334 and the free longitudinal edges of the anode are welded to two stem leads 368. These leads are held in properly spaced relation by a pair of straps 339, one above and one below the electrodes, the ends of the straps being welded to the stem leads 368 and the intermediate portion being channeled and snugly embracing an insulated rod 334. Second grid 386 has two parallel spaced apart rectangular frame sections 387 connected together by bars 388 at the upper and lower end of the grid sections, along one edge of the sections and these connecting bars are provided with channel sections to fit over a rod 334.

Each of the other edges of the grid frames has, at the upper and lower ends thereof, a right angularly bent car 389, each of the lower ears being welded to a stem lead 380, and both the upper pair of cars and the lower pair of ears being connected by straps 381 welded to the ears and channeled to snugly fit about an insulated rod 334.

Cathode tensioning spring support 362 is mounted on the bare part of a rod 334, the lower bare end of this rod being welded to stem lead 382. The filamentary cathode is tensioned by the spring 364 mounted on the support 362, the lower end of the cathode being welded via tabs to angled stem lead 383. Unfiashed getter 344 bridges the two stem leads 368 near the upper ends thereof.

In Figs. 17 to 20 there is illustrated a tetrode with four insulated spacers 434. In these figures there is illustrated a filamentary cathode 442, a first or control grid 436, a second grid 486 and an anode 438. In this form of invention, the four electrodes and rods are in the form of a package held in compacted relation by the welding together of the lateral ends of portions of the second grid 486 and of portions of the plates constituting the anode 438. The cathode, its support and connections are essentially as described in connection with Figs. 5 to 8. This is likewise true of the first or control grid 436. The frame sections of the second grid 486 are cut away at each of their corners, as at 487 and the shortened-in-height wings of the second grid are channeled and partially bent around the insulated rods 434, the ends of the wings being inclined toward each other and finally arranged in parallel relation and welded together. The anode plates 438 are generally rectangular in shape with ears 439 at each corner of the plates bent in toward the rods 434 and with the oppositely positioned ears welded to one another. The anode plates each have angle brackets 476 welded thereto, the angle brackets also having channeled portions 478 welded to stem leads 474. The second grid 486 is electrically welded to a stem lead 488. The unfiashed getter is mounted on the stem leads 474 and a reinforcing bar 490 is Welded to the two rods 434 opposite the tension spring support.

It is obvious from the examples given about that the invention is capable of being carried out in still other various forms and therefore the invention should not be limited except as defined by the following claims.

We claim as our invention:

1. A stack comprised of a tightly held assembly ineluding insulating rods, at least one of which has an electro-conductive core, and electrodes including a cathode, a grid, and an anode, the conductive core forming part of the electrical circuit to one of the electrodes, the grid being held against movement and spaced from said anode by said insulating rods, and means supporting the cathode adjacent the grid.

2. A stack comprised of a tightly held assembly including insulating rods, at least one of which has an electro-conductive core, a cathode electrically connected to the core, a grid, and an anode, the grid being held 6 against movement and spaced from said anode by said insulating rods.

3. A stack comprised of a grid having a rectangular frame, a pair of insulated rods engaging the frame above and below the same at each of two parallel edges of the frame, a pair of anode plates parallel to the grid frame and engaging the four rods on sides thereof opposite to the sides engaging the grid frame, said plates being secured together at the edges which are parallel to the rods, and a second two frame grid engaging the insulating rods on the same side as the anode plates engage the rods and having the frame edges parallel to the rods secured together.

4. A structure as defined in claim 1 in which the grid is a rectangular frame, the rods being arranged in pairs, one pair engaging the frame above and the other below the same at each of two parallel edges of the frame, the anode comprising a pair of plates parallel to the grid frame and engaging the four rods on sides thereof opposite to the sides engaging the grid frame, said plates being secured together at the edges which are parallel to the rods.

5. A structure as defined in claim 4 in which a second two frame grid is provided engaging the insulating rods on the same side as the anode plates engage the rods and also having the frame edges parallel to the rods secured together.

References Cited in the file of this patent UNITED STATES PATENTS 2,064,981 Knoll Dec. 22, 1936 2,197,526 Kosack Apr. 16, 1940 2,355,083 Kn'm Aug. 8, 1944 2,413,006 Spencer Dec. 24, 1946 2,463,635 McIntosh Mar. 8, 1949 2,503,806 Diggie Apr. 11, 1950 2,660,688 Walsh Nov. 24, 1953 

